AP Physics I - Unit 1: Kinematics

Displacement

indicates how far an object ends up from its initial position, regardless of its total distance traveled

Average velocity

is displacement divided by the time interval over which that displacement occurred

Instantaneous velocity

how fast an object is moving at a specific moment in time

Acceleration

tells how much an object’s speed changes in one second

position time graph

• To determine how far from the detector an object is located, look at the vertical axis of the position-time graph

• To determine how fast an object is moving, look at the steepness (i.e. the slope) of the position-time graph

• To determine which way the object is moving, look at which way the position-time graph is sloped.

• A position-time slope like a front slash / means the object is moving away from the detector

• A position slope like a back slash \ means the object is moving toward the detector

Velocity-time graph

• To determine how fast an object is moving, look at the vertical axis of the velocity-time graph

• To determine which way the object is moving, look at whether the velocity-time graph is above or below the horizontal axis

• An object is moving away from the detector if the velocity-time graph is above the horizontal axis

• An object is moving toward the detector if the velocity-time graph is below the horizontal axis

• To determine how far an object travels, determine the area between the velocity-time graph and the horizontal axis

• On a velocity-time graph it is not possible to determine how far from the detector the object is located

Acceleration

• When an object speeds up, its acceleration is in the direction of motion

• When an object slows down, its acceleration is opposite the direction of motion

• Objects in free fall gain or lose 10m/s of speed every second

Projectile motion

• Angled velocities must be broken down into x and y velocity components

• Vx0 = Vxf because az = 0m/s/s unless told otherwise.

• Objects will always experience a vertical acceleration ay = 10m/s/s Down

• Time to travel horizontally (x) is the same time to travel vertically (y)

• When an object is in free-fall, 

  • its VERTICAL acceleration is always 10 m/s per second. 

  • its HORIZONTAL acceleration is always zero.

• Facts about the Peak (Max Height)

  • Vy at the peak is 0m/s